Silicon nitride film, a semiconductor device, a display device and a method for manufacturing a silicon nitride film

ABSTRACT

The present invention provides a method for forming by plasma CVD a silicon nitride film that can be formed over heat-sensitive elements as well as an electroluminescent element and that has favorable barrier characteristics. Further, the present invention also provides a semiconductor device, a display device and a light-emitting display device formed by using the silicon nitride film. In the method for forming a silicon nitride film by plasma CVD, silane (SiH 4 ), nitrogen (N 2 ) and a rare gas are introduced into a deposition chamber in depositing, and the reaction pressure is within the range from 0.01 Torr to 0.1 Torr.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a silicon nitride film and amanufacturing method thereof and specifically, to a high quality siliconnitride film and a method for manufacturing the same with comparativelycold temperature. Further, the present invention relates to asemiconductor device that is superior in reliability.

2. Description of the Related Art

There are various electronic device products with technical progress inthe world. Conditions required for these products become severe year byyear, and long-term reliability is taken for granted as well asenhancing style and performance.

Various elements such as pixels and semiconductor elements are used forsuch electronic devices, but there are some devices which tend todeteriorate by being exposed to an atmospheric component (such as wateror oxygen).

Deterioration of elements forming an electronic device decreases thereliability of the electronic device in itself. Thus, the abovedescribed elements which easily deteriorate are often given withprotective measures.

There are methods for filling an atmosphere to which an element isexposed, with an inert gas or providing it with a desiccant, as typicalprotective measures.

In addition, there is a measure that an element that easily deterioratesis covered with a material that does not easily transmit suchdeterioration factors. As the materials, silicon nitride, silicon oxide,silicon nitride oxide, carbon nitride, carbon are cited. A film made ofthe materials has barrier characteristics against a particular gas andthus, serves effectively as a protective film for an element.

It is known that silicon nitride has barrier characteristics againstmoisture or oxygen but the degree is different according to filmformation conditions. In general, silicon nitride is denser and hasbetter barrier characteristics, as the etching rate of a particularetching solution is smaller. Further, variation of barriercharacteristics is thought to be related to variation of filmcomposition depending on film formation conditions.

By the way, an electroluminescent (EL) element is given as example ofthe element in which deterioration is promoted by a substancepenetrating from the outside like this. Since an electroluminescentelement uses an organic material or a combination material of aninorganic material and an organic material as an electroluminescentlayer, the electroluminescent element easily deteriorates due tomoisture or oxygen.

The electroluminescent element is mainly expected to be applied todisplays and the like. However, as the result of deterioration of anelectroluminescent element due to oxygen or moisture, generation of adark spot or progress of a shrinkage is accelerated and the elementlacks the reliability as a product and is difficult to practically use.Thus, it is extremely necessary to protect an electroluminescent elementfrom moisture or oxygen and to enhance the reliability.

There is a method for manufacturing a silicon nitride film containingless hydrogen for preventing deterioration of an element due to moistureor oxygen, and the like (Reference: Japanese Patent Laid-Open No. H9-205209).

A barrier film made of a silicon nitride film that does not easilypenetrate moisture or oxygen is preferably formed for such anelectroluminescent element. Although there are various methods forforming a protective film, plasma CVD is preferably employed since theplasma CVD can give good productivity and coverage.

The barrier film is, however, formed as a top layer, and thus, needs tobe formed at the heat-resistance temperature or less of elements formedunder the barrier film. For example, when an interlayer insulating filmis made of acrylic, the permissible temperature is 100° C. or less inview of problems such as degasification. Naturally, it is not preferablethat an EL element is heated at higher temperature than necessary.

However, for forming a silicon nitride film having enough barriercharacteristics by a conventional plasma CVD, a substrate is needed tobe heated at the temperatures from 300° C. to 400° C., thus, it isdifficult to apply the plasma CVD to heat-sensitive elements.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a method for formingby plasma CVD a silicon nitride film that can be formed overheat-sensitive elements as well as an EL element and that has favorablebarrier characteristics.

Further, it is another object of the present invention to provide asemiconductor device, a display device and a light-emitting displaydevice formed by using the silicon nitride film.

In order to achieve the objects, a method for forming a silicon nitridefilm by plasma CVD according to the present invention is a method bywhich silane (SiH₄), nitrogen (N₂) and a rare gas are introduced into adeposition chamber in depositing, and the reaction pressure is withinthe range from 0.01 Torr to 0.1 Torr.

Another structure of the present invention is that the flow-rate ratioof the SiH₄ gas to the N₂ gas and a rare gas (SiH₄/N₂ and rare gas) is0.002 or more and less than 0.006 in the above structure.

Another structure of the present invention is that the reactiontemperature is within the temperatures from 60° C. or more to less than85° C. in the above structure.

Another structure of the present invention is that the rare gas is anyone of helium (He), neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe)in the above structure.

A silicon nitride film that can achieve the objects comprises a rare gaselement of 0.3 atomic % or more; and characteristics that etching rateon a buffered hydrogen fluoride including HF of 4.7% and NH₄F of 36.3%at room temperature (20-25° C.) is 30.0 nm/min or less.

Another structure is that a silicon nitride film that can achieve theobjects comprises a rare gas element of 0.3 atomic % or more; hydrogenof less than 25 atomic %; and characteristics that etching rate on abuffered hydrogen fluoride including HF of 4.7% and NH₄F of 36.3% atroom temperature is 30.0 nm/min or less.

Another structure is that a silicon nitride film that can achieve theobjects comprises a rare gas element of 0.3 atomic % or more; oxygen of4.0 atomic % or more; and characteristics that etching rate on abuffered hydrogen fluoride including HF of 4.7% and NH₄F of 36.3% atroom temperature is 30.0 nm/min or less.

Another structure is that a silicon nitride film that can achieve theobjects comprises a rare gas element of 0.3 atomic % or more; oxygen of4.0 atomic % or more; hydrogen of less than 25 atomic %; andcharacteristics that etching rate on a buffered hydrogen fluorideincluding HF of 4.7% and NH₄F of 36.3% at room temperature is 30.0nm/min or less.

Another preferable structure is that a silicon nitride film that canachieve the objects comprises characteristics that etching rate is 20.0nm/min or less in the above described structure.

Another preferable structure of a silicon nitride film is that thehydrogen concentration is less than 20 atomic % in the above describedstructure.

Another preferable structure of a silicon nitride film is that theoxygen concentration is 4.0 atomic % or more and less than 10 atomic %in the above described structure.

A structure of the present invention that can achieve the objects isthat a semiconductor device comprises the silicon nitride film.

A structure of the present invention that can achieve the objects isthat a display device comprises the silicon nitride film.

A structure of the present invention that can achieve the objects isthat a light emitting display device comprises the silicon nitride film.

According to the present invention, a dense silicon nitride film havinggood barrier characteristics can be manufactured at a low temperature.

In even a heat-sensitive element, penetration of moisture or oxygen canbe prevented effectively by using a silicon nitride film of the presentinvention as a barrier film without deterioration due to heat. Further,not only reliability of an element but also reliability of asemiconductor device, a display device, a light-emitting display deviceor an electronic device that incorporates the element can be enhanced.

These and other objects, features and advantages of the presentinvention become more apparent upon reading of the following detaileddescription along with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIGS. 1A and 1B are conceptual views of a CVD apparatus of the presentinvention;

FIG. 2 shows a relation between an etching rate and a flow-rate ratio ofdeposition gases (SiH₄/N₂+Ar);

FIGS. 3A to 3C show an example of a method for manufacturing a displaydevice;

FIGS. 4A to 4C show an example of an auxiliary wiring;

FIG. 5 is a top view of an example of a module configuration; and

FIGS. 6A to 6E each show an example of electronic devices according tothe present invention.

DETAILED DESCRIPTION OF THE INVENTION Embodiment Modes Embodiment Mode 1

A method for manufacturing a dense silicon nitride film by plasma CVDunder conditions of substrate temperature of 80° C. is describedhereinafter. When the substrate temperature is too low, quality ofplasma becomes bad and thus, a favorable film cannot be formed. On thecontrary, when the substrate temperature is too high, an element formedbelow the film deteriorates. Consequently, the substrate temperature ispreferably within the range from 60° C. to 85° C. 80° C. is favorable,since the element below the film is less damaged and a favorable plasmastate can be obtained, when the substrate temperature is set to 80° C.

FIG. 1A is a conceptual diagram of a plasma CVD apparatus used in thisembodiment mode. An RF plasma CVD of 13.56 MHz is employed in thisembodiment mode and a sheath is formed on the plasma side of eachelectrode to generate self-bias voltage as shown in FIG. 1B. In thisembodiment mode, a substrate is installed on an electrode A side to forma film.

Silane (SiH₄), nitrogen (N₂) and a rare gas are used as deposition gasesin the present invention. Argon (Ar) is used as the rare gas in thisembodiment mode. The gas flow rate of SiH₄:N₂:Ar is 2:300:500 [sccm]. Itis one feature of the present invention to use a rare gas. As shown inTable 1, most of rare gases such as Ar and He can generate stable plasmaeven with low energy, since they show low voltage in startingdischarging.

TABLE 1 Gas He Ar N₂ O₂ Discharge Voltage (kV/cm) 3.7 6.7 35.4 27.1Metastable State Energy (eV) 20.61 11.72 6.17 1.63 Metastable State Life(sec) 6 × 10⁵ more 2 7 than 1.3 Diffusion Coefficient 400~600 49   146 —(cm² · s⁻¹ · Torr) Ionization Energy (eV) 24.58 15.76 15.5 12.1

As apparent from helium (He) shown in Table 1, energy in startingdischarging of rare gases is generally low and thus, stable plasma canbe obtained. Rare gases such as helium (He), neon (Ne), krypton (Kr),and xenon (Xe) can be adopted in addition to argon (Ar). The gases areeach an inert gas and thus, does not influence a chemical reaction forforming silicon nitride.

By the way, it is known that plasma generated by the rare gases has apositive electric charge and is accelerated by a sheath to collideagainst the electrode. This is called an ion bombardment. When this ionbombardment is used positively, it is thought to be efficient that asubstrate is set on the electrode K side on which potential differencewith a plasma region is large. (FIG. 1B)

On the contrary, when an effect of the ion bombardment is used, thesubstrate is not set commonly on the electrode A side in which apotential difference with the plasma region is small. However, thesubstrate is daringly formed on the electrode A side in which thepotential difference with the plasma region is small, according to thepresent invention. This is because deposition is promoted by givingmoderate ion bombardment and a dense film having an improved filmquality is formed.

Referentially the etching rate of a silicon nitride film formed whenargon gas is not introduced in the same structure as above is about 55nm/min. However, the etching rate when Ar is introduced is about 28nm/min. Thus, a dense film whose etching rate becomes about twice asslow as the above described rate is obtained by an effect of rare gas.

Other conditions are shown in Table 2.

TABLE 2 Substrate Deposition Substrate Substrate Temperature Pressure RFPower Position Glass 80° C. 0.1 Torr 13.56 MHz 300 W Gap 30 mm

Although the silicon nitride film is formed at cold temperature of 80°C. in the above conditions, the etching rate (room temperature: 20-25°C.) in buffered hydrogen fluoride including HF of 4.7% and NH₄F of 36.3%(made by Morita Chemical Industries Co., Ltd, 110—Buffered HydrogenFluoride) is 29.59 nm/min, and the etching rate (room temperature) inLAL500 (made by Stella Chemifa Corporation) is 30.19 nm/min. As aresult, a dense film that is favorable in quality is obtained.

In this manner, a method of the present invention makes it possible toobtain a silicon nitride film which shows the etching rate as describedabove and which has favorable barrier characteristics.

Then, composition of the silicon nitride film of the present inventionformed under the above conditions is shown in Table 3. Composition of asilicon nitride film formed at the normal temperature (substratetemperature of 325° C.) under the condition of not employing Ar is shownin Table 4 as a comparative example. It should be noted that about theamount of hydrogen, although difference in SIMS data is not seen somuch, no less than 10% difference is shown in RBS data. It is thoughtthat the reason is that the amount of hydrogen is close to detectionsaturation in SIMS measurement.

TABLE 3 Density Concentration Hydrogen Nitrogen Oxygen Argon (atoms/cm³)SIMS 1.3 × 10²² Detection 7.1 × 3.6 × 1.10 × 10²³ (atoms/cm³) Saturation10²¹ 10²⁰ RBS 15 46.7 7.2 0.3 (atomic %)

TABLE 4 Density Concentration Hydrogen Nitrogen Oxygen Argon (atoms/cm³)SIMS (atoms/cm³) 1.0 × 10²² Detection 3.0 × 10¹⁷ Less than the 1.11 ×10²³ Saturation Minimum Limit of Detection RBS (atomic %) 25 44 — — FlowRate: SiH4:NH3:N2:H2 = 30:240:300:60[SCCM] Pressure: 1.20 Torr RF power:13.56 MHz 150 W

In addition, the etching rate of the silicon nitride film of thecomparative example is 35.0 nm/min in the room temperature in the LAL500(made by Stella Chemifa Corporation). The etching rate in the LAL500 ofthe silicon nitride of the present invention is 30.19 nm/min in the roomtemperature. As the result thereof, it is apparent that the siliconnitride film of the present invention is as dense and favorable inquality as or denser and more favorable in quality than the siliconnitride film of the comparative example, although the silicon nitridefilm of the present invention is formed at low temperature of 80° C.

A notable point in results (Table 3, Table 4) of these compositionanalysis is existence of a rare gas (Ar) and oxygen, and the amount ofhydrogen in the silicon nitride film of the present invention. The raregas (Ar) is an essential gas for a method for manufacturing the siliconnitride film of the present invention, and occupies a bigger ratio ofthe flow-rate ratio. Therefore, a rare gas (Ar) is included in thesilicon nitride film of the present invention. A rare gas (Ar) becomesequal to or less than the minimum limit of detection in the conventionalsilicon nitride film formed without a rare gas (Ar). The rare gas (Ar)concentration in the silicon nitride film of the present invention is0.3 atomic % in this experimental result, but the concentration of therare gas (Ar) is at least 0.2 atomic %, preferably within the range from0.3 atomic % to 0.7 atomic %.

Then, the amount of oxygen is given as characteristic composition. Theamount of oxygen of the silicon nitride film of the present invention iscomparatively large and it can be also regarded as a silicon oxide film.However, because the measurement result of the refractive index shows arefractive index of a silicon nitride film, it can be said that the filmformed by a method for manufacturing of the present invention is asilicon nitride film. Therefore, the silicon nitride film of the presentinvention can be referred to as a silicon nitride film including muchoxygen.

In addition, the film stress of a silicon nitride film is usuallytensile stress. However, the film stress of a silicon oxynitride filmhaving the oxygen concentration of about 60 atomic % becomes compressivestress, and as the oxygen concentration in the film becomes higher, itis understood that film stress shows a tendency of compression. On theother hand, the silicon nitride film of the present invention shows anevident tendency of compressive stress. It is thought that this is aninfluence of oxygen included in the film. The stress becomes compressivestress from tensile stress, and therefore, the silicon nitride film ofthe present invention is a film which has favorable adhesiveness andwhich is hard to peel.

The oxygen concentration in the silicon nitride film of the presentinvention is 2 atomic % or more, and when it is from 2 atomic %, to 10atomic %, preferably from 2 atomic % to 8 atomic %, bettercharacteristics can be obtained.

Lastly, as for the amount of hydrogen, the amount of hydrogen includedin the silicon nitride film of the present invention is smaller thanthat of the silicon nitride film formed by high temperature plasma CVDconventionally as a comparative example. It is an established theorythat the content of hydrogen in a film becomes high in the case of lowtemperature CVD. However, the silicon nitride film of the presentinvention contains less hydrogen, even when forming it at low depositiontemperature of 80° C. Thus, electronic devices using the silicon nitridefilm of the present invention does not easily cause defects due todegasification, even when a heat treatment is performed thereon in aprocess after forming the silicon nitride film of the present invention.

Note that the hydrogen concentration of the silicon nitride film of thepresent invention is from 1 atomic % to 25 atomic %, from 5 atomic % to20 atomic % for better characteristics, preferably, from 10 atomic % to16 atomic %.

Such several distinctive characteristics are specific to a siliconnitride film manufactured by a method for manufacturing a siliconnitride film (temperature, gas kind, flow-rate ratio) according to thepresent invention and these characteristics can make even a film formedat low temperature of 80° C. extremely dense and favorable in thecharacteristics.

Embodiment Mode 2

This embodiment mode shows examined results of parameter in depositing,which is thought to have a large influence on film quality. Note thatparameter in forming a silicon nitride film of the present invention isdetermined based on the results.

Table 5 shows a compared result of etching rate of silicon nitride filmswhich are formed by changing only reaction pressure under the sameconditions. Etching is performed on buffered hydrogen fluoride includingHF of 4.7% and NH₄F of 36.3% (made by Morita Chemical Industries Co.,Ltd, 110—Buffered Hydrogen Fluoride) at room temperature.

TABLE 5 Etching rate Pressure (Torr) (Å/min) 0.1 275 0.2 more than 2600

This shows that the etching rate is about ten times higher, whendeposition pressure is changed from 0.1 Torr to 0.2 Torr. Although theresult shows that a favorable film is thought to be formed with a lowerdeposition pressure, the deposition speed is slower as the depositionpressure is lower. Thus, the deposition pressure of from 0.01 Torr to0.1 Torr is appropriate.

FIG. 2 shows a compared result of etching rate of a silicon nitride filmthat is formed with changed deposition gas flow-rate ratio. The etchingrate is obtained by performing etching also on a buffered hydrogenfluoride including HF of 4.7% and NH₄F of 36.3% (made by Morita ChemicalIndustries Co., Ltd, 110—Buffered Hydrogen Fluoride) at roomtemperature.

The flow-rate ratio of the deposition gases (SiH₄/(N₂+Ar)) indicatesminimum value in the vicinity of from 0.006 to 0.008. As the degree ofdenseness of the silicon nitride film, since an etching rate of 30.0nm/min or less (preferably, 20.0 nm/min) is the value that can bearpractical use from the viewpoint of barrier characteristics, thedeposition is preformed under conditions of the flow-rate ratio of atleast 0.002. In addition, light-transmittance of the film decreases whenthe flow-rate ratio of SiH₄ is large. Thus, the flow-rate ratio of SiH₄to N₂+Ar is preferably within in the range from 0.002 to 0.006 when thesilicon nitride film is formed as a passivation film on a light-emissionside in a display device.

The silicon nitride film that is formed under the above-mentioneddeposition conditions, even when it is formed at 100° C. or less,preferably from 60° C. to 85° C., shows characteristics shown inEmbodiment Mode 1 and is dense and favorable in barrier characteristics.

Embodiment Mode 3

This embodiment mode shows an example of using a silicon nitride film ofthe present invention as a passivation film of an electroluminescentdisplay device with reference to FIGS. 3A to 3C.

Base insulating films 301 a and 301 b are formed on a substrate 100. Thesubstrate 100 may be an insulating substrate such as a crystallineglass, a glass substrate or a quartz substrate, a ceramic substrate, astainless substrate, a metal substrate (tantalum, tungsten, molybdenumand the like), a semiconductor substrate, a plastic substrate(polyimide, acryl, polyethylene terephthalate, polycarbonate,polyarylate, polyethersulfone and the like), or a substrate which canresist the heat generated in a process. A glass substrate is used inthis embodiment mode.

The base insulating films 301 a and 301 b are formed with a single layeror lamination of two or more of insulating films such as a silicon oxidefilm, a silicon nitride film, and a silicon oxynitride film. These filmsare formed by using a known method such as sputtering, reduced pressureCVD, or plasma CVD. This embodiment mode employs a lamination of twolayers; however, a single layer or a lamination of three or more layersmay be employed as well. In this embodiment mode, the insulating layer301 a as the first layer is formed from a silicon nitride oxide film of50 nm in thickness, and the insulating layer 301 b as the second layeris formed from a silicon oxynitride film of 100 nm in thickness. Itshould be noted that the silicon nitride oxide film and the siliconoxynitride film are different in the proportion of nitrogen and oxygen.The former has more nitrogen than the latter.

Subsequently, an amorphous semiconductor film is formed. The amorphoussemiconductor film may be formed from silicon or a silicon-basedmaterial (for example Si_(x)Ge_(1-x) and the like) of from 25 nm to 80nm (preferably from 30 nm to 60 nm) in thickness. As a manufacturingmethod, a known method such as sputtering, low pressure CVD, or plasmaCVD may be used. In this embodiment mode, the amorphous semiconductorfilm is formed from amorphous silicon of 50 nm in thickness.

Subsequently, the amorphous silicon is crystallized. In this embodimentmode, the amorphous silicon is doped with an element for promotingcrystallization, and heated to be crystallized. After thecrystallization by the heat treatment, laser crystallization may beperformed.

A thin layer containing nickel is formed on the surface of thesemiconductor film by applying by using a spinner a nickel acetatesolution or a nickel nitrate solution containing nickel in aconcentration of 5 to 10 ppm. The nickel element may be scattered on thewhole surface of the semiconductor film by sputtering instead ofapplying by spinner. As a catalytic element, one or a plurality of theelements such as iron (Fe), palladium (Pd), tin (Sn), lead (Pb), cobalt(Co), platinum (Pt), copper (Cu), gold (Au) may be used as well asnickel (Ni).

Subsequently, the amorphous semiconductor film is crystallized byheating. It may be carried out at temperatures from 500° C. to 650° C.for about 4 to 24 hours since a catalytic element is used. Thesemiconductor film becomes a crystalline semiconductor film by thiscrystallization treatment.

The crystalline semiconductor film is etched to form crystallinesemiconductor layers each having a desired shape 302 to 305, afterforming the crystalline semiconductor film. Note that thecrystallization treatment may be performed after a semiconductor layeris etched to have a desired shape as an amorphous semiconductor layer.

Then, the semiconductor film is crystallized by a laser to improve thecrystallinity. As a laser oscillator, a pulsed or a continuous wave gasor solid state and a metal laser oscillator may be used to perform alaser crystallization. As a gas laser, excimer laser, Ar laser, Kr laserand the like may be used, while as a solid state laser, YAG laser, YVO₄laser, YLF laser, YAlO₃ laser, glass laser, ruby laser, alexandritelaser, sapphire laser may be used, and helium cadmium laser, coppersteam laser, gold steam laser may be used as a metal laser. One or aplurality of the elements Cr³⁺, Cr⁴⁺, Nd³⁺, Er³⁺, Ce³⁺, Co²⁺, Ti³⁺,Yb³⁺, or V³⁺ is doped to a crystal of laser medium of a solid statelaser as an impurity.

A laser beam oscillated from a laser oscillator may be emitted in alinear shape by using an optical system. The linear laser beam can beobtained by using a conventional cylindrical lens or a concave mirror.The laser beam may be irradiated with the power density in the range offrom 0.01 MW/cm² to 100 MW/cm² in the atmospheric air, an atmosphere ofwhich oxygen concentration is controlled, an N₂ atmosphere, or invacuum. Further, in the case of using a pulsed laser, it is preferablethat the frequency is from 30 Hz to 300 Hz and the laser energy densityis from 100 mJ/cm² to 1500 mJ/cm² (representatively from 200 mJ/cm² to500 mJ/cm²). The laser beam may be irradiated while overlapping by 50 to98% by calculating with FWHM.

Further, gettering of nickel used for crystallization may be performed.A method for gettering is given as the next method, for example. Thesurface is treated with ozone water first, and then a barrier film isformed in thickness of from 1 nm to 5 nm, and a gettering site is formedon the barrier film by sputtering. The gettering site is formed bydepositing an amorphous silicon film containing argon element of 150 nmin thickness. The gettering site is formed under deposition conditions:deposition pressure of 0.3 Pa, a flow rate of gas (Ar) of 50 (sccm),deposition power of 3 kW and substrate temperature of 150° C. Further,the atomic concentration of the argon element included in the amorphoussilicon film falls in the range of from 3×10²⁰/cm³ to 6×10²⁰/cm³ and theatomic concentration of oxygen falls in the range of from 1×10¹⁹/cm³ to3×10¹⁹/cm³ under the above-described conditions. Thereafter, getteringis carried out by heating at 650° C. for 3 minutes by using a lampannealing device. The gettering region may be removed by etching.

Next, a gate insulating layer 306 is formed. An insulating layercontaining silicon may be formed in thickness of approximately 115 nm bylow pressure CVD, plasma CVD, sputtering or the like. A silicon oxidefilm of 10 nm thick is formed in this embodiment mode. The silicon oxidefilm can be formed by mixing and discharging TEOS (Tetraethyl OrthoSilicate) and O₂ by the plasma CVD with a reaction pressure of 40 Pa,the substrate temperature of from 300° C. to 400° C., the high frequency(13.56 MHz) power density in the range of from 0.5 W/cm² to 0.8 W/cm².The thus prepared silicon oxide film has an excellent characteristics asa gate insulating film by the subsequent heating at temperatures from400° C. to 500° C.

Subsequently, a first conductive film of from 20 nm to 100 nm thick isformed over the gate insulating film and a second conductive film offrom 100 nm to 400 nm thick is formed over the first conductive film. Inthis embodiment mode, a tantalum nitride (TaN) film of 30 nm inthickness is formed as the first conductive layer and a tungsten (W)film of 370 nm in thickness is formed as the second conductive layer.The TaN film and the W film may be both formed by sputtering. The TaNfilm may be formed in a nitride atmosphere by using Ta as a target, andthe W film may be formed by using W as a target. Low resistance ispreferable for using it as a gate electrode, in particular theresistance of the W film is preferably 20 μΩcm or less. Therefore, highpurity (99.9999%) target of W is desirably used and further attentionhas to be paid not to let impurities in during deposition. Theresistance of the W film formed like this can be from 9 μΩcm to 20 μΩcm.

Note that the first conductive layer is a TaN film and the secondconductive layer is a W film in this embodiment mode, however, the firstand second conductive layers are not limited thereto and may be formedof any element of Ta, W, Ti, Mo, Al, Cu, Cr, and Nd, or an alloymaterial or a compound material mainly containing the aforementionedelement. Furthermore, a semiconductor film represented by apolycrystalline silicon film doped with an impurity element such asphosphorous may be used. An AgPdCu alloy may be utilized as well. Acombination thereof may be selected appropriately. In this embodimentmode, the lamination of two layers are employed; however, one layer orthree or more layers may be laminated as well.

In order to form electrodes and wirings by etching the conductive layer,a mask of resist is formed through exposure to light by photolithographyand etching is carried out.

A first etching is performed under first and second etching conditions.A gate electrode and wirings are formed by etching with the mask ofresist. The etching conditions may be selected appropriately.

Herein, ICP (Inductively Coupled Plasma) etching is employed. As thefirst etching conditions, CF₄, Cl₂, and O₂ are used as etching gaseswith the gas-flow ratio of 25/25/10 (sccm), and at a pressure of 1.0 Pa,an RF power of 500 W (13.56 MHz) is applied on the coil electrode togenerate plasma to conduct etching. An RF power of 150 W (13.56 MHz) isapplied to a substrate (sample stage) side to apply a substantiallynegative self bias voltage. The W film is etched under the first etchingconditions to make the edges of the first conductive layer to have atapered shape. An etching rate on the W film under the first etchingconditions is 200.39 nm/min, the etching rate on the TaN layer is 80.32nm/min, and the selectivity ratio of W to TaN is approximately 2.5.Further, the taper angle of the W film is about 26° under the firstetching conditions.

Subsequently, etching is carried out under the second etchingconditions. Etching is performed for about 15 seconds with the mask madeof resist left, by using CF₄ and Cl₂ as etching gases with the gas-flowratio of 30/30 (sccm), and at a pressure of 1.0 Pa, an RF power of 500 W(13.56 MHz) is applied on the coil electrode to generate plasma toconduct etching. An RF power of 20 W (13.56 MHz) is applied to asubstrate (sample stage) side to apply a substantially negative selfbias voltage. Under the second etching conditions in which CF₄ and Cl₂are mixed, both of the W film and the TaN film are etched to the sameextent. The gate insulating layer which is not covered with electrodesis etched by about from 20 nm to 50 nm in this first etching.

The edge portions of the first and second conductive layers becometapered in the first etching due to the bias voltage applied to thesubstrate side. As described, a conductive layer having a first shapethat is made of the first and second conductive layers is formed in thefirst etching.

The second etching is carried out without removing the mask made ofresist. The second etching is performed using SF₆, Cl₂, and O₂ asetching gases with the gas-flow ratio of 24/12/24 (sccm), and at apressure of 1.3 Pa, an RF power of 700 W (13.56 MHz) is applied on thecoil electrode to generate plasma to conduct etching for about 25seconds. An RF power of 10 W (13.56 MHz) is applied to a substrate(sample stage) side to apply a substantially negative self bias voltage.The W film is selectively etched by this etching to form a conductivelayer having a second shape 307 a to 310 a and 307 b to 310 b.

A first doping is carried out without removing the mask of resist. Thus,an N-type impurity is doped in a low concentration to the crystallinesemiconductor layers 302 to 305. The first doping may be performed byion doping or ion implantation. The ion doping may be performed with thedosage of 1×10¹³ to 5×10¹⁴ atoms/cm², and an acceleration voltage offrom 40 kV to 80 kV. The ion doping is carried out at an accelerationvoltage of 50 kV in this embodiment mode. The N-type impurity may be anelement of the group 15 of the periodic table represented by phosphorous(P) or arsenic (As). Phosphorous (P) is used in this embodiment mode.The first conductive layers 307 a to 310 a is used as a mask to form afirst impurity region (N⁻ region) to which an impurity of lowconcentration is doped, in a self-aligned manner.

Subsequently, the mask made of resist is removed. Then, a new mask madeof a resist is formed to cover a region for forming a low concentrationimpurity region of the semiconductor layer 304 and the semiconductorlayers 303 and 305 for forming a p-channel TFT and the second doping iscarried out at a higher acceleration voltage than the first doping. Then-type impurity is added in the second doping as well. The ion dopingmay be performed with the dosage of 1×10¹³ to 3×10¹⁵ atoms/cm², and anacceleration voltage of from 60 kV to 120 kV. The ion doping is carriedout with the dosage of 3.0×10¹⁵ atoms/cm² and an acceleration voltage of65 kV in this embodiment mode. The second doping is carried out so thatthe impurity element is doped into the semiconductor layer under thefirst conductive layer by using the second conductive layer as a maskagainst the impurity element.

By the second doping, a second impurity region 311 (N⁻ region, Lovregion) is formed on the part where the second conductive layers 307 bto 310 b are not overlapped or the part which is not covered with themask in the part where the crystalline semiconductor layers 302 to 305is overlapped with the first conductive layers 307 a to 310 a. TheN-type impurity is doped into the second impurity region 311 at theconcentration ranging from 1×10¹⁸ atoms/cm³ to 5×10¹⁹ atoms/cm³.Further, the exposed parts 312, 313 (third impurity region: N⁺ region)which are not covered with either the first shaped conductive layers 307a to 310 a nor the mask is doped at a high concentration N-type impurityranging from 1×10¹⁹ atoms/cm³ to 5×10²¹ atoms/cm³. The semiconductorlayer 304 has an N⁺ region, a part 314 of which is covered only with themask. The concentration of the N-type impurity of this part is notchanged from the concentration of the impurities doped in the firstdoping.

Note that each impurity region is formed by two doping treatments inthis embodiment mode; however, the invention is not limited to this. Theimpurity region having a desired impurity concentration may be formed byone or a multiple doping by determining the condition appropriately.

Subsequently, the mask made of resist is removed and a new mask formedof a resist is formed over the semiconductor layers 302 and 304 thatform an n-channel TFT to conduct a third doping. Fourth impurity regions(P⁺ region) 315 and 316 and a fifth impurity regions (P⁻ region) 317 and318 into which an impurity element having the opposite conductivity tothe ones of the first and second conductive layers is added, are formedby the third doping in the semiconductor layer forming a p-channel TFT.

In the third doping, the fourth impurity region (P⁺ region) is formed onthe parts 315 and 316 which are not covered with the mask of resist andnot overlapped with the first conductive layer. The fifth impurityregion (P⁻ region) is formed on the parts 317 and 318 which are notcovered with the mask of resist, but which are overlapped with the firstconductive layer, and not overlapped with the second conductive layerThe P⁻ type impurity element may be boron (B), aluminum (Al), gallium(Ga) or the like, each of which are of the group 13 of the periodictable.

In this embodiment mode, boron is used as a P-type impurity element toform the fourth and fifth impurity regions by ion doping using diborane(B₂H₆). Ion doping is carried out with the dosage of 1×10¹⁶ atoms/cm²and an acceleration voltage of 80 kV.

The fourth impurity regions (P⁺ region) 315 and 316 and the fifthimpurity regions (P⁻ region) 317 and 318 are doped with phosphorous ofdifferent concentrations by the first and second doping. However, in allof the fourth impurity regions (P⁺ region) 315, 316 and the fifthimpurity regions (P⁻ region) 317, 318, the third doping is performed sothat the concentration of the P-type impurity element is 1×10¹⁹ to5×10²¹ atoms/cm². Therefore, the fourth impurity regions (P⁺ region) 315and 316 and the fifth impurity regions (P⁻ region) 317 and 318 serve assource region and drain region of a p-channel TFT without problems.

The fourth impurity regions (P⁺ region) 315 and 316 and the fifthimpurity regions (P⁻ region) 317 and 318 are formed by once of thirddoping in this embodiment mode, however, the present invention is notlimited to this. The fourth impurity regions (P⁺ region) 315 and 316 andthe fifth impurity regions (P⁻ region) 317 and 318 may be formed bymultiple doping treatments according to each doping condition.

Subsequently, the mask of resist is removed to form a first passivationlayer 319. As the first passivation layer, an insulating film containingsilicon is formed in thickness of from 100 nm to 200 nm by plasma CVD orsputtering. In this embodiment mode, a silicon oxynitride film is formedin thickness of 100 nm by plasma CVD. In the case of using a siliconoxynitride film, a silicon oxynitride film formed of SiH₄, N₂O, and NH₃by plasma CVD, or a silicon oxynitride silicon film formed of SiH₄ andN₂O may be used. In this case, the film is formed with a reactionpressure of from 20 Pa to 200 Pa, a substrate temperature of 300 to 400°C., and a high frequency (60 MHz) electronic density from 0.1 W/cm² to1.0 W/cm². Further, a silicon oxynitride hydride film formed of SiH₄,N₂O, and H₂ may be employed as the first passivation layer 319. It isneedless to say that the first passivation layer 319 is not limited to asingle layer structure of the silicon oxynitride film as in thisembodiment mode, but other insulating layer containing silicon having asingle or a laminated structure may be utilized.

Thereafter, crystallinity of the semiconductor layer is recovered andthe impurity element doped in the semiconductor layer is activated byheating (heat treatment). Heating may be performed under the conditionsof oxygen concentration of 1 ppm or less, preferably in the nitrogenatmosphere of 0.1 ppm or less, at a temperatures from 400° C. to 700° C.In this embodiment mode, the semiconductor layer is activated by heatingat a temperature of 410° C. for one hour. Note that laser annealing orrapid thermal annealing (RTA) may be employed instead of heating.

By heating the semiconductor layer after forming the first passivationlayer 319, it can be hydrogenated as well as activated. Hydrogenation isa method by which a dangling bond in the semiconductor layer isterminated by hydrogen in the first passivation layer 319.

A heat treatment may be carried out before forming the first passivationlayer 319; however, it is preferable to carry out the heat treatmentafter forming the first passivation layer 319 in order to protectwirings and the like, as in this embodiment mode, in the case where thematerials constituting first conductive layers and second conductivelayers are sensitive to heat. Further, in the case of heating beforeforming the first passivation layer, hydrogenation by using hydrogencontained in the passivation layer cannot be performed since the firstpassivation layer 319 is not formed yet.

In this case, hydrogenation may be performed by using hydrogen excitedby plasma (plasma hydrogenation) or by heating at temperatures from 300°C. to 450° C. for 1 to 12 hours in an atmosphere containing from 3% to100% of hydrogen.

Subsequently, a first interlayer insulating layer 320 is formed on thefirst passivation layer 319. The first interlayer insulating layer 320may be an inorganic insulating layer or an organic insulating layer. Theinorganic insulating layer may be a silicon oxide film formed by CVD, asilicon oxide film applied by SOG (Spin On Glass). The organicinsulating layer may be a film of polysiloxane, polyimide, polyamide,BCB (benzocyclobutene), acryl or positive photosensitive organic resin,negative photosensitive organic resin and the like. Also, a laminationof an acryl film and an silicon oxynitride film may be used.

An acryl film is formed in thickness of 1.6 μm in this embodiment mode.By the first interlayer insulating layer 320, concavo-convex portionsdue to the TFTs can be alleviated and planarized. The first insulatinglayer 320 plays a significant role in planarization, therefore, aneasily planarized material is preferably used for it.

Thereafter, a second passivation film 321 made of a silicon nitride filmof the present invention may be formed over the first interlayerinsulating film 320. The second passivation film may be formed inthickness of about from 10 nm to 200 nm, which can protect the firstinterlayer insulating film 320 from moisture. The second passivationfilm 321 may be formed by the method of Embodiment Mode 1.

The second passivation film 321, the first interlayer insulating film320 and the first passivation film 319 are etched to form contact holesto reach the third impurity regions 312 and 313 and the fourth impurityregions 315 and 316.

Subsequently, wirings 322 to 328 and an electrode 329 which electricallyconnect to each impurity region are formed. It should be noted thatthese wirings are formed by patterning the lamination of a Ti film of 50nm in thickness and an alloy film (Al and Ti) of 500 nm in thickness. Itis needless to say that the lamination is not limited to two-layerlamination, and a signal layer or three or more layers may be laminatedas well. Further, the material for the wirings is not limited to Al andTi. For example, a lamination in which an Al film or a Cu film may beformed on the TaN film and then the Ti film is formed thereon may bepatterned to form wirings.

Thus, a semiconductor device of the present invention shown in FIG. 3Acan be obtained.

A TFT of the present invention shown in FIG. 3A is formed and then afirst electrode 400 formed of a transparent conductive film is formed soas to partially overlap with a wiring 327 of the TFT. The transparentconductive film is preferably formed by using a material with a highwork function, for example, a compound of indium oxide and tin oxide(ITO), a compound of indium oxide and zinc oxide, zinc oxide, tin oxide,indium oxide, titanium nitride or the like can be used. Alternatively,the transparent conductive film added with gallium, an ITO film formedby sputtering using a target mixed with SiO₂ may be used. The firstelectrode 400 serves as an anode of the light emitting element. In thisembodiment mode, ITO is used as the first electrode 400. The ITO isformed in thickness of 0.1 μm by sputtering.

Subsequently, an insulator 401 is formed so as to cover the edge face ofthe electrode. The insulator 401 can be formed from an inorganic ororganic material. It is advantageous to form it by using aphotosensitive organic material since a break in the film and the likedo not occur easily in an opening portion in depositing a light-emittinglayer and better coverage can be obtained.

Thereafter, the substrate is removed of dusts and the like by wipingwith a PVA (polyvinyl alcohol)-based porous material. It should be notedthat in this embodiment mode, fine powder (dusts) generated when the ITOand the insulating layer are etched are removed by wiping with thePVA-based porous material.

Subsequently, PEDOT may be applied on the whole surface and baked as apretreatment before depositing a light emitting layer. At this time, itis preferable to rinse the substrate after applying PEDOT, and thenapply PEDOT again, since PEDOT is not good in wettability with ITO.Then, the substrate is heated at reduced pressure atmosphere aftervaporizing moisture by heating at normal pressure. It should be notedthat the substrate is heated at 170° C. at reduced pressure atmospherefor four hours after applying PEDOT, and then naturally cooled for 30minutes.

Then, the substrate is deposited by moving an evaporation source with adeposition apparatus. For example, deposition is performed in adeposition chamber which is vacuum evacuated to 5×10⁻³ Torr (0.665 Pa)or less, preferably to 10⁻⁴ to 10⁻⁶ Torr. When the deposition isperformed, an organic compound is vaporized by resistive heating inadvance and scatters in the direction of the substrate when a shutter isopened in deposition. The vaporized organic compound scatters upwardlyand is deposited on the substrate through the opening portion providedon a metal mask to form a light emitting layer 402 (including a holetransport layer, a hole injection layer, an electron transport layer,and an electron injection layer).

An example in which the light-emitting layer 402 is formed by depositionis shown here, however, the invention is not limited to this. Alight-emitting layer formed of high-molecular material may be formed byan application method (such as spin coating or inkjet). Further, thisembodiment mode describes an example in which layers formed of alow-molecular material are laminated as an organic compound layer,however, a layer formed of a high-molecular material and a layer formedof a low-molecular material may be laminated as well. In addition, RGBlight emitting layers may be formed to achieve full color display, or inthe case of forming a monochrome light emitting layer, full colordisplay may be achieved by using a color conversion layer or a colorfilter. In addition, inorganic materials may be used as well.

It is assumed that a light emitting element emits light in such a waythat an electron injected from cathode and a hole injected from anodeform a molecular exciton by recombining at the center of light emissionin an organic compound layer when voltage is applied to between a pairof electrodes with the organic compound layer therebetween, and energyis discharged to emit light when the molecular exciton returns to theground state. The exciton state is known to include a singlet excitonand a triplet exciton, through either of which light can be emitted.

A light emitting layer typically has a laminated structure. The typicallaminated structure is constituted as “a hole transport layer, anelectroluminescent layer, and an electron transport layer”. Thisstructure has such a high luminous efficiency that the light emittingdevices which are recently researched and developed mostly employ thisstructure. The structure in which a hole injection layer, a holetransport layer, an electroluminescent layer, and an electron transportlayer are laminated on the anode, or a structure in which a holeinjection layer, a hole transport layer, an electroluminescent layer, anelectron transport layer, and an electron injection layer are laminatedin these orders may be employed as well. A fluorescent pigment and thelike may be doped into the electroluminescent layer.

It should be noted that all the layers provided between the cathode andanode are referred to as a light emitting layer collectively in thisspecification. Therefore, the above described hole injection layer, holetransport layer, electroluminescent layer, electron transport layer andelectron injection layer are all included in the light emitting layer.These layers can be formed of any one or an appropriate combination of alow-molecular weight organic compound material, a medium-molecularweight organic compound material, or a high-molecular weight organiccompound material. In addition, a mixed layer of an electron transportmaterial and a hole transport material, or a mixed junction in which amixed region is formed in each junction boundary may be formed. Further,an inorganic light emitting material may be used instead of the organicmaterial.

Subsequently, a second electrode 403 is formed as a cathode over thelight emitting layer 402. The second electrode 403 may be formed from athin film containing a metal with a small work function (such as Li, Mg,or Cs). In addition, it is preferable that the second electrode be madeof a laminated film in which a transparent conductive film (ITO (alloyof indium oxide and tin oxide), an alloy of indium oxide and zinc oxide(In₂O₃—ZnO), or zinc oxide (ZnO), or the like) is laminated on the thinfilm containing Li, Mg, Cs, or the like. Further, the second electrodemay be formed in thickness of from 0.01 μm to 1 μm by electron beamdeposition, although the film thickness may be determined appropriatelyto serve as a cathode.

In the case of using the electron beam deposition, radioactive rays aregenerated when the acceleration voltage is too high, thereby damaging aTFT. On the other hand, in the case where the acceleration voltage istoo low, a deposition rate is lowered and the productivity is decreased.In view of the foregoing problems, the second electrode 403 is formednot to be thicker than the thickness enough to serve as a cathode. Whenthe cathode is thin, the productivity is not affected so much even whenthe deposition rate is low. Although resistance may become higher due tothe thin cathode in this case, this problem can be solved by laminatinga low resistance metal such as Al on the cathode by resistive heating,sputtering or the like.

Over the insulator 401 and the second electrode 403, a silicon nitridefilm of the present invention is formed as a third passivation layer404. The second passivation layer 321 and the third passivation layer404 are both made of a film which hardly penetrate the substance such asmoisture or oxygen which deteriorate a light emitting element. Since thesilicon nitride film of the present invention is dense, it can be usedeffectively for the passivation film which does not easily penetratesubstances that cause deterioration of such light emitting element.Further, the light emitting element is less damaged by heat, since thedeposition temperature of 100° C. or less, (preferably from 60° C. to85° C.) and the silicon nitride film is extremely favorable. EmbodimentMode 1 may be referred to concerning a method for forming the thirdpassivation film.

As for the flow-rate ratio of the deposition gases, light-transmittanceof a film is not limited in particular, in the case of an example inwhich light is emitted through the substrate side (bottom) as shown inFIG. 3B. Thus, the flow-rate ratio of the deposition gases (SiH₄/(N₂+Ar)may be selected within the range from 0.002 to 0.012.

Thus, a light emitting element shown in FIG. 3B can be obtained.Although not shown, a plastic film is provided as a sealing materialthereon and an inert gas is filled between the light emitting elementand the sealing agent. Then, the substrate is connected to an externalterminal by an FPC (Flexible Printed Circuit) by using anisotropicconductive film to complete a light emitting display device (displaymodule) of the present invention.

FIG. 3B shows an example in which light is emitted from the substrateside (bottom). Light can also be emitted from the top in a laminatedstructure shown in FIG. 3C. In that case, the second electrode may beformed from a light-transparent material. Further, the third passivationfilm is preferably enough light-transparent. In the case of using thesilicon nitride film of the present invention, the flow-rate ratio ofthe deposition gases (SiH₄/(N₂+Ar)) may be selected within the rangefrom 0.002 to 0.006.

Since a silicon nitride film of the present invention is used as thepassivation film of a light-emitting layer, it is possible to form adense silicon nitride film that does not easily penetrate oxygen ormoisture, over a light-emitting element, without damaging an interlayerinsulating film or an light-emitting element due to heat. It is alsopossible to suppress deterioration of a semiconductor device or alight-emitting element and to obtain a semiconductor device and alight-emitting element of the present invention that can enhance thereliability greatly.

Embodiment Mode 4

In this Embodiment Mode, an example in which a silicon nitride film ofthe present invention is formed as a passivation film of an auxiliarywiring formed by a droplet discharging method (such as ink-jetting) isdescribed with reference to FIG. 4A to 4C. FIG. 4A is a top conceptualview of a light-emitting display device manufactured in FIGS. 3A to 3C.

An auxiliary wiring is drawn by a droplet discharging method (such asink-jetting) by using a nozzle of a droplet discharging apparatus asshown in FIG. 4B. FIG. 4B shows a cross-sectional view of one pixel in apixel portion shown in FIG. 4A. The auxiliary wiring is formed on atransparent electrode 73 that serves as a cathode of a light-emittingelement in order to reduce resistance of the whole electrode. Further,the auxiliary wiring also serves as a light-shielding film, therebyenhancing contrast.

When this auxiliary wiring is formed by a droplet discharging method, asolution dispersed with metal nanoparticles is discharged. However, inthe case of using a metal such as silver, in particular, that easilymigrates, there is a fear that the periphery is likely to becontaminated by the wiring material. At the time, migration of a metalis prevented by covering with a dense film having good barriercharacteristics such as a silicon nitride film of the present invention,as shown in FIG. 4C, thereby preventing contamination. The auxiliarywiring is formed in an upper portion of an electroluminescent element,but since it is possible to form a silicon nitride film of the presentinvention at a temperature of 100° C. or less (preferably, from 60° C.to 85° C.), a passivation film can be formed without damaging anelectroluminescent element by heat in depositing, thereby making itpossible to manufacture a light-emitting display device having betterreliability.

Embodiment Mode 5

In this embodiment mode, appearance of a panel of a light-emittingdevice corresponding to one mode of the present invention is describedwith reference to FIG. 5. FIG. 5 is a top view of the panel in which atransistor and a light-emitting element that are formed on a substrateare sealed by a sealing material between the substrate and an oppositesubstrate 4006.

A sealing material 4005 is provided to surround a pixel portion 4002, asignal processing circuit 4003, and a scanning line driver circuit 4004formed on a substrate 4001. In addition, the opposite substrate 4006 isprovided over the pixel portion 4002, the signal processing circuit4003, a signal line driver circuit 4020 and the scanning line drivercircuit 4004. Thus, the pixel portion 4002, the signal processingcircuit 4003, the signal line driver circuit 4020 and the scanning linedriver circuit 4004 are hermetically sealed with a filler by thesubstrate 4001, the sealing material 4005 and the opposite substrate4006.

The pixel portion 4002, the signal processing circuit 4003, the signalline driver circuit 4020 and the scanning line driver circuit 4004 thatare each formed over the substrate 4001 each include plural thin filmtransistors.

A leading wiring corresponds to a wiring for supplying signals or powersupply voltage to the pixel portion 4002, the signal processing circuit4003, the signal line driver circuit 4020 and the scanning line drivercircuit 4004. The leading wiring is connected to a connection terminal4016 and the connection terminal is electrically connected to a terminalof a flexible print circuit (FPC) 4018 through an anisotropic conductivefilm.

As the filler, in addition to an inert gas such as nitrogen or argon, anultraviolet ray curable resin or a thermosetting resin can be used.Polyvinyl chloride, acryl, polyimide, epoxy resin, silicone resin,polyvinyl butyral, or ethylene-vinylene acetate can be used.

The display device of the present invention includes a panel in which apixel portion having a light-emitting element is formed and a module inwhich an IC is mounted on the panel.

Embodiment Mode 6

Electronic devices of the present invention mounting a module, anexample of which is shown in Embodiment Mode 5, include a video camera,a digital camera, a goggle type display (head mounted display), anavigation system, an audio player (such as a car audio compo) acomputer, a game machine, a portable information terminal (such as amobile computer, a cellular telephone, a portable game machine or anelectronic book), an image reproducing device provided with recordingmedium (typically, a device provided with a display that can reproduce arecording medium such as DVD (digital versatile disc) and display theimage) and the like. Practical examples thereof are shown in FIGS. 6A to6E.

FIG. 6A shows a light-emitting display device. And a television imagereceiver or a monitor of a computer is given as an example of the lightemitting display device. The light emitting display device includes acasing 2001, a display portion 2003, a speaker portion 2004 and thelike. The reliability of the display portion 2003 or other mountedsemiconductor devices is enhanced by the light-emitting display deviceof the present invention. A polarizing plate or a circular polarizingplate may be provided for a pixel portion to improve the contrast. Filmsmay be provided in the order of a quarter wavelength plate, a halfwavelength plate, a polarizing plate. Further, an antireflection filmmay be provided over the polarizing plate.

FIG. 6B shows a cellular phone including a main body 2101, a casing2102, a display portion 2103, a sound input portion 2104, a sound outputportion 2105, an operation key 2106, an antenna 2108, and the like. Thereliability of the display portion 2103 or other mounted semiconductordevices is enhanced in the cellular phone of the present invention.

FIG. 6C shows a computer including a main body 2201, a casing 2202, adisplay portion 2203, a keyboard 2204, an external connection port 2205,a pointing mouse 2206, and the like. The reliability of the displayportion 2203 or other mounted semiconductor devices is enhanced in thecomputer of the present invention. FIG. 6C shows a laptop computer as anexample, but the present invention can be applied to a desktop computerin which a hard disc and a display portion are united, and the like.

FIG. 6D shows a mobile computer including a main body 2301, a displayportion 2302, a switch 2303, operation keys 2304, an infrared port 2305and the like. The reliability of the display portion 2302 or othermounted semiconductor devices is enhanced in the mobile computer of thepresent invention.

FIG. 6E shows a portable game machine including a casing 2401, a displayportion 2402, a speaker portion 2403, operation keys 2404, a port forinserting a recording medium 2405 and the like. The reliability of thedisplay portion 2402 or other mounted semiconductor devices is enhancedin the portable game machine of the present invention

As described above, the present invention can be applied extremelywidely and used for electronics of all fields.

This application is based on Japanese Patent Application serial no.2003-189045 filed in Japan Patent Office on 30, Jun. 2003, the contentsof which are hereby incorporated by reference.

Although the present invention has been fully described by way ofEmbodiment Modes with reference to the accompanying drawings, it is tobe understood that various changes and modifications will be apparent tothose skilled in the art. Therefore, unless such changes andmodifications depart from the scope of the present invention hereinafterdefined, they should be constructed as being included therein.

1. A silicon nitride film comprising: a rare gas element of 0.3 atomic %or more, wherein an etching rate of the silicon nitride film on abuffered hydrogen fluoride including HF of 4.7% and NH₄F of 36.3% atroom temperature is 30.0 nm/min or less.
 2. A silicon nitride filmaccording to claim 1, wherein the rare gas is any one of helium (He),neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe).
 3. A siliconnitride film according to claim 1, wherein an etching rate of thesilicon nitride is 20.0 nm/min or less.
 4. A semiconductor devicecomprising the silicon nitride film according to claim
 1. 5. A displaydevice comprising the silicon nitride film according to claim
 1. 6. Alight emitting display device comprising the silicon nitride filmaccording to claim
 1. 7. A silicon nitride film comprising: a rare gaselement of 0.3 atomic % or more; and hydrogen of less than 25 atomic %,wherein an etching rate of the silicon nitride film on a bufferedhydrogen fluoride including HF of 4.7% and NH₄F of 36.3% at roomtemperature is 30.0 nm/min or less.
 8. A silicon nitride film accordingto claim 7, wherein the hydrogen concentration is less than 20 atomic %.9. A silicon nitride film according to claim 7, wherein the rare gas isany one of helium (He), neon (Ne), argon (Ar), krypton (Kr), and xenon(Xe).
 10. A silicon nitride film according to claim 7, wherein anetching rate of the silicon nitride is 20.0 nm/min or less.
 11. Asemiconductor device comprising the silicon nitride film according toclaim
 7. 12. A display device comprising the silicon nitride filmaccording to claim
 7. 13. A light emitting display device comprising thesilicon nitride film according to claim
 7. 14. A silicon nitride filmcomprising: a rare gas element of 0.3 atomic % or more; and oxygen of4.0 atomic %, or more; and wherein an etching rate of the siliconnitride film on a buffered hydrogen fluoride including HF of 4.7% andNH₄F of 36.3% at room temperature is 30.0 nm/min or less.
 15. A siliconnitride film according to claim 14, wherein the oxygen concentration isless than 4.0 atomic % or more and less than 10 atomic %.
 16. A siliconnitride film according to claim 14, wherein the rare gas is any one ofhelium (He), neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe).
 17. Asilicon nitride film according to claim 14, wherein an etching rate ofthe silicon nitride is 20.0 nm/min or less.
 18. A silicon nitride filmaccording to claim 14, wherein the hydrogen concentration is less than20 atomic %.
 19. A semiconductor device comprising the silicon nitridefilm according to claim
 14. 20. A display device comprising the siliconnitride film according to claim
 14. 21. A light emitting display devicecomprising the silicon nitride film according to claim
 14. 22. A siliconnitride film comprising: a rare gas element of 0.3 atomic % or more;oxygen of 4.0 atomic %, or more; hydrogen of less than 25 atomic %; andwherein an etching rate of the silicon nitride film on a bufferedhydrogen fluoride including HF of 4.7% and NH₄F of 36.3% at roomtemperature is 30.0 nm/min or less.
 23. A silicon nitride film accordingto claim 22, wherein the rare gas is any one of helium (He), neon (Ne),argon (Ar), krypton (Kr), and xenon (Xe).
 24. A silicon nitride filmaccording to claim 22, wherein an etching rate of the silicon nitride is20.0 nm/min or less.
 25. A silicon nitride film according to claim 22,wherein the hydrogen concentration is less than 20 atomic %.
 26. Asilicon nitride film according to claim 22, wherein the oxygenconcentration is less than 4.0 atomic % or more and less than 10 atomic%.
 27. A semiconductor device comprising the silicon nitride filmaccording to claim
 22. 28. A display device comprising the siliconnitride film according to claim
 22. 29. A light emitting display devicecomprising the silicon nitride film according to claim 22.